<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="wrap">
        <button class="btn">删除</button>
        <div class="list">
            <li class="first">01</li>
            <li>02</li>
            <li class="mid">03</li>
            <li>04</li>
            <li>05</li>
            <li class="last">06</li>
            <!-- <li>07</li> -->
        </div>
    </div>
</body>
<script>
    // 节点的删除
    // 1. 自删    Element.remove()   => 返回的undefined

    // 2. 父删    parent.removeChild(node)  => 父元素统筹



    var list = document.getElementsByClassName("list")[0];
    var mid = document.getElementsByClassName("mid")[0];
    var btn = document.getElementsByClassName("btn")[0];


    // 点击新增按钮 删除对应节点
    btn.onclick = function () {
        // 自删 
        // var result = mid.remove();  // 返回值undefined
        // console.log(result);

        // 父删   => 重复删除会报错(The node to be removed is not a child of this node.)
        if (mid) {//mid存在 
            var re = list.removeChild(mid);
            mid = null;  //清除mid
            console.log(re);
        }
    }


</script>

</html>